Chromium compounds and uses thereof

ABSTRACT

Inorganic oxides, modified with a metal alkyl and an unsaturated hydrocarbon, can be used to support a metal source, such as, for example, chromium, and a pyrrole-containing compound. The resultant catalyst system can be used to trimerize olefins. Olefin trimerization processes are also provided.

BACKGROUND OF THE INVENTION

This invention relates to chromium catalysts to oligomerize olefins.This invention also relates to a process to oligomerize olefins.

Supported chromium oxide cataysts have been a dominant factor in theproduction of olefin polymers, such as polyethylene or copolymers ofethylene and hexene. Supported chromium catalysts can be used in avariety of polymerization processes. Additionally, most known chromiumcompounds must be supported to be catalytically active and mostsupported chromium compounds are useful only for olefin polymerization.If an olefin copolymer is desired, the polymerization process becomesmore complex, in that two different monomers must be fed to thepolymerization reactor.

Olefin trimerization and oligomerization catalysts are also known in theart, but usually lack selectivity to a desired product and have a lowproduct yield. However, olefin trimerization and/or oligomerization, ifdone efficiently, is a process to provide useful olefins. These olefinicproducts can be further trimerized, oligomerized and/or, optionally,incorporated into a polymerization process.

SUMMARY OF THE INVENTION

Therefore, it is an object of this invention to provide novel inorganicoxide catalyst supports.

It is another object of this invention to provide a process to prepareinorganic oxide catalyst supports.

It is yet another object of this invention to provide an improved olefinoligomerization catalyst system.

It is still another object of this invention to provide an improvedprocess to oligomerize olefins.

Therefore, in accordance with one embodiment of this invention, aninorganic oxide is treated with a metal alkyl and an unsaturatedhydrocarbon to form a novel inorganic oxide catalyst support. Inaccordance with another embodiment of this invention, the resultantsupport can be contacted with a chromium source and a pyrrole-containingcompound to form a catalyst system. The catalyst system can be used tooligomerize olefins, with high selectivity to a desired olefin product.

DETAILED DESCRIPTION OF THE INVENTION Supports

Catalyst supports useful in this invention can be any conventionalpolymerization catalyst support. Preferably, one or more refractorymetal inorganic oxides comprise the catalyst support. Exemplaryrefractory metal inorganic oxide catalyst supports include, but are notlimited to, inorganic oxides, either alone or in combination, phosphatedinorganic oxides and mixtures thereof. Particularly preferred inorganicoxide supports are selected from the group consisting of silica,silica-alumina, alumina, fluorided alumina, silated alumina, thoria,aluminophosphate, aluminum phosphate, phosphated silica, phosphatedalumina, silica-titania, preprecipitated silica/titania,fluorided/silated alumina and mixtures thereof. Furthermore, any one ormore of these supports can contain chromium.

The catalyst supports can be prepared in accordance with any methodknown in the art. Exemplary support method preparations are given inU.S. Pat. Nos. 3,887,494; 3,900,457; 4,053,346; 4,294,724; 4,392,990;4,405,501; and 4,364,855, hereinafter incorporated by reference.Presently, the most preferred catalyst support, because of the greatestcatalytic activity and selectivity, is aluminophosphate, as disclosed inU.S. Pat. No. 4,364,855 (1982).

The metal alkyl can be any heteroleptic or homoleptic metal alkylcompound. One or more metal alkyls can be used. The alkyl ligand(s) onthe metal can be aliphatic and/or aromatic. Preferably, the alkylligand(s) are any saturated or unsaturated aliphatic radical. The metalalkyl can have any number of carbon atoms. However, due to commercialavailability and ease of use, the metal alkyl will usually comprise lessthan about 70 carbon atoms per metal alkyl molecule and preferably lessthan about 20 carbon atoms per molecule. Exemplary metal alkyls include,but are not limited to, alkylaluminum compounds, alkylboron compounds,alkylmagnesium compounds, alkylzinc compounds and/or alkyl lithiumcompounds. Exemplary metal alkyls include, but are not limited to,n-butyl lithium, s-butyllithium, t-butyllithium, diethylmagnesium,diethylzinc, triethylaluminum, trimethylaluminum, triisobutylaluminum,and mixtures thereof.

Preferably, the metal alkyl is selected from the group consisting ofnon-hydrolyzed, i.e., not pre-contacted with water, alkylaluminumcompounds, derivatives of alkylaluminum compounds, halogenatedalkylaluminum compounds, and mixtures thereof for improved productselectivity, as well as improved catalyst system reactivity, activity,and/or productivity. Exemplary compounds include, but are not limitedto, triethylaluminum, tripropylaluminum, tributylaluminum,diethylaluminum chloride, diethylaluminum bromide, diethylaluminumethoxide, ethylaluminum sesquichloride, and mixtures thereof for bestcatalyst system activity and product selectivity. The most preferredalkylaluminum compound is triethylaluminum, for best results in catalystsystem activity and product selectivity.

Most preferably, the metal alkyl is a non-hydrolyzed alkylaluminumcompound, expressed by the general formulae AlR₃, AlR₂ X, AlRX₂, AlR₂OR, AlRXOR, and/or Al₂ R₃ X₃, wherein R is an alkyl group and X is ahalogen atom. Exemplary compounds include, but are not limited to,triethylaluminum, tripropylaluminum, tributylaluminum,diethylaluminumchloride, diethylaluminumbromide,diethylaluminumethoxide, diethylaluminum phenoxide, ethylaluminumethoxy-chloride, and/or ethylaluminum sesquichloride. Preferably, metal alkylis a trialkylaluminum compound, AlR₃, and the most preferredtrialkylaluminum compound is triethylaluminum, for reasons given above.

The unsaturated hydrocarbon can be any aromatic or aliphatichydrocarbon, in a gas, liquid or solid state. Preferably, to effectthorough contacting of the inorganic oxide and metal alkyl, theunsaturated hydrocarbon will be in a liquid state. The unsaturatedhydrocarbon can have any number of carbon atoms per molecule. Usually,the unsaturated hydrocarbon will comprise less than about 70 carbonatoms per molecule, and preferably, less than about 20 carbon atoms permolecule, due to commercial availability and ease of use. Exemplaryunsaturated, aliphatic hydrocarbon atoms include, but are not limitedto, ethylene, 1-hexene, 1,3-butadiene, and mixtures thereof. Exemplaryunsaturated, aromatic hydrocarbons include, but are not limited to,toluene, benzene, xylene, mesitylene, hexamethylbenzene, and mixturesthereof. Unsaturated, aromatic hydrocarbons are preferred in order toimprove catalyst system stability, as well as produce a highly activecatalyst system in terms of activity and selectivity. The most preferredunsaturated aromatic hydrocarbon is toluene, for best resultant catalystsystem stability and activity.

The inorganic oxide, metal alkyl, and unsaturated hydrocarbon can becontacted and mixed at any time, temperature and pressure to thoroughlycontact the inorganic oxide with the metal alkyl and unsaturatedhydrocarbon. For ease of use, ambient temperatures and pressures arepreferred. Mixing times can be up to about 24 hours, preferably, lessthan about 10 hours, and most preferably, from one second to 8 hours.Longer times usually provide no additional benefit and shorter times canbe insufficient for thorough contacting.

After the inorganic oxide, metal alkyl, and unsaturated hydrocarbon havebeen thoroughly contacted, the mixture can be stored until needed forfurther use. Preferably, the mixture is stored under a dry, inertatmosphere. Optionally, the liquid can be decanted or filtered off anddiscarded from the inorganic oxide support. The resultant treated,inorganic oxide support can be dried, if desired, and then stored,preferably, under a dry, inert atmosphere until needed for later use.

Catalyst Systems

Catalyst systems prepared in accordance with this invention can be usedpreferably for olefin oligomerization. Catalyst systems comprise atreated inorganic oxide support, as disclosed earlier, a metal source,and a pyrrole-containing compound. If a solid, treated inorganic oxidesupport has been separated and recovered from the catalyst supportpreparation mixture, the catalyst system further comprises a metal alkyland an unsaturated hydrocarbon compound.

The metal source can be any metal catalytically active to oligomerizeolefins. Exemplary metal sources are selected from the group consistingof chromium, nickel, cobalt, iron, molybdenum, and copper. Preferably,catalyst systems comprise a chromium source as the metal source for bestresultant catalyst system activity and product selectivity.

If a chromium source is used, the chromium source can be one or moreorganic or inorganic chromium compounds, wherein the chromium oxidationstate is from 0 to 6. As used in this disclosure, chromium metal isincluded in this definition of a chromium source. Generally, thechromium source will have a formula of CrX_(n), wherein X can be thesame or different and can be any organic or inorganic radical, and n isan integer from 1 to 6. Exemplary organic radicals can have from about 1to about 20 carbon atoms per radical, and are selected from the groupconsisting of alkyl, alkoxy, ester, ketone, and/or amido radicals. Theorganic radicals can be straight-chained or branched, cyclic or acyclic,aromatic or aliphatic, can can be made of mixed aliphatic, aromatic,and/or cycloaliphatic groups. Exemplary inorganic radicals include, butare not limited to halides, sulfates, and/or oxides.

Preferably, the chromium source is a chromium(II)- and/orchromium(III)-containing compound which can yield a catalyst system withimproved oligomerization activity. Most preferably, the chromium sourceis a chromium(III) compound because of ease of use, availability, andenhanced catalyst system activity. Exemplary chromium(III) compoundsinclude, but are not limited to, chromium carboxylates, chromiumnaphthenates, chromium halides, chromium pyrrolides, and/or chromiumdionates. Specific exemplary chromium(III) compounds include, but arenot limited to, chromium(III) 2,2,6,6-tetramethylheptanedionate[Cr(TMHD)₃ ], chromium(III) 2-ethylhexanoate [Cr(EH)₃ ], chromium(III)naphthenate [Cr(Np)₃ ], chromium(III) chloride, chromium(III)tris(2-ethylhexanoate), chromous bromide, chromic bromide, chromouschloride, chromic chloride, chromous fluoride, chromic fluoride,chromium(III) oxy-2-ethylhexanoate, chromium(III)dichloroethylhexanoate, chromium(III) acetylacetonate, chromium(III)acetate, chromium(III)butyrate, chromium(III) neopentanoate,chromium(III) laurate, chromium(III) stearate, and/or chromium(III)oxalate.

Specific exemplary chromium(II) compounds include, but are not limitedto, chromium(II) bis(2-ethylhexanoate), chromium(II) acetate,chromium(II) butyrate, chromium(II) neopentanoate, chromium(II) laurate,chromium(II) stearate, chromium(II) oxalate and/or chromium(II)pyrrolides.

The pyrrole-containing compound can be any pyrrole-containing compoundthat will react with a chromium source to form a chromium pyrrolidecomplex. As used in this disclosure, the term "pyrrole-containingcompound" refers to hydrogen pyrrolide, i.e., pyrrole, (C₄ H₅ N),derivatives of hydrogen pyrrolide, as well as metal pyrrolide complexes.A "pyrrolide" is defined as a compound comprising a 5-membered,nitrogen-containing heterocycle, such as, for example, pyrrole,derivatives of pyrrole, and mixtures thereof. Broadly, thepyrrole-containing compound can be pyrrole and/or any heteroleptic orhomoleptic metal complex or salt, containing a pyrrolide radical, orligand. The pyrrole-containing compound can be either affirmativelyadded to the reaction, or generated in-situ.

Generally, the pyrrole-containing compound will have from about 1 toabout 20 carbon atoms per molecule. Exemplary pyrrolides are selectedfrom the group consisting of hydrogen pyrrolide (pyrrole), lithiumpyrrolide, sodium pyrrolide, potassium pyrrolide, cesium pyrrolide,and/or the salts of substituted pyrrolides, because of high reactivityand activity with the other reactants. Examples of substitutedpyrrolides include, but are not limited to, pyrrole-2-carboxylic acid,2-acetylpyrrole, pyrrole-2-carboxaldehyde, tetrahydroindole,2,5-dimethylpyrrole, 2,4-dimethyl-3-ethylpyrrole,3-acetyl-2,4-dimethylpyrrole,ethyl-1-2,4-dimethyl-5-(ethoxycarbonyl)-3-pyrrole-propionate,ethyl-3,5-dimethyl-2-pyrrolecarboxylate. When the pyrrole-containingcompound contains chromium, the resultant chromium compound can becalled a chromium pyrrolide.

The most preferred pyrrole-containing compounds used in aoligomerization catalyst system, prepared in accordance with thisinvention, are selected from the group consisting of hydrogen pyrrolide,i.e., pyrrole (C₄ H₅ N) and/or 2,5-dimethylpyrrolole. While allpyrrole-containing compounds can produce catalyst systems with highactivity and productivity, use of pyrrole and/or 2,5-dimethylpyrrololecan produce a catalyst system with enhanced activity and selectivity toa desired oligomerized product, such as, for example, theoligomerization of ethylene to 1-hexene, as well as decreased polymer,i.e., solids, production.

Optionally, and preferably, a halide source is also present in thereaction mixture comprising a treated inorganic oxide support, achromium source and a pyrrole-containing compound. The presence of ahalide source in the reaction mixture can increase catalyst systemactivity and productivity, as well as increase product selectivity.Exemplary halides include, but are not limited to fluoride, chloride,bromide, and/or iodide. Due to ease of use and availability, chloride isthe preferred halide. Based on improved activity, productivity, and/orselectivity, bromide is the most preferred halide.

The halide source can be any compound containing a halogen. Exemplarycompounds include, but are not limited to, compounds with a generalformula of R_(m) X_(n), wherein R can be any organic and/or inorganicradical, X can be a halide, selected from the group consisting offluoride, chloride, bromide, and/or iodide, and m+n can be any numbergreater than 0. If R is an organic radical, preferably R has from about1 to about 70 carbon atoms per radical and, most preferably from 1 to 20carbon atoms per radical, for best compatibility and catalyst systemactivity. If R is an inorganic radical, preferably R is selected fromthe group consisting of aluminum, silicon, germanium, hydrogen, boron,lithium, tin, gallium, indium, lead, and mixtures thereof. Specificexemplary compounds include, but are not limited to, methylene chloride,chloroform, benzylchloride, silicon tetrachloride, tin(II) chloride,tin(IV) chloride, germanium tetrachloride, boron trichloride, aluminumtribromide, aluminum trichloride, 1,4-di-bromobutane, and/or1-bromobutane. Most preferably, the halide source is selected from thegroup consisting of tin (IV) halides, germanium halides, and mixturesthereof.

Furthermore, the chromium source, the metal alkyl and/or unsaturatedhydrocarbon can contain and provide a halide to the reaction mixture.Preferably, the halide source is an alkylaluminum halide and is used inconjunction with alkylaluminum compounds due to ease of use andcompatibility, as well as improved catalyst system activity and productselectivity. Exemplary alkylaluminum halides include, but are notlimited to, diisobutylaluminum chloride, diethylaluminum chloride,ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminumbromide, diethylaluminum iodide, and mixtures thereof.

The amount of each reactant used to prepare an oligomerization catalystsystem can be any amount sufficient that, when combined with one or moreolefins, oligomerization, as defined in this disclosure, occurs.

As disclosed earlier, if a dried, treated inorganic oxide support iscombined with a metal source and a pyrrole-containing compound,preferably a metal alkyl and an unsaturated hydrocarbon are alsore-contacted with the catalyst system. The metal alkyl and unsaturatedhydrocarbon can be any metal alkyl and unsaturated hydrocarbon, asdisclosed earlier.

The catalyst system components can be combined in any manner underconditions suitable to form an effective catalyst system and can beprepared either external to an oligomerization reactor, or in-situ in anoligomerization reactor. The reaction preferably occurs in the absenceof oxygen, which can deactivate the catalyst, and under anhydrousconditions, i.e., in the initial absence of water. Therefore a dry,inert atmosphere, such as, for example, nitrogen and/or argon is mostpreferred.

When an oligomerization catalyst system is prepared prior to addition toan oligomerization reactor, a solid catalyst system can be recoveredaccording to any method known in the art. Recovery of a solid catalystsystem can help reduce, or eliminate, the presence of any unsaturatedhydrocarbon(s), which are not oligomerization reactants, can beoligomerization reaction poisons. For example, aromatic hydrocarbons,such as, for example, excess toluene, can poison an oligomerizationreaction.

Preferably, a solid catalyst system is recovered by filtration andsubsequently washed with a sufficient amount of a saturated hydrocarbon.Saturated hydrocarbons useful for washing include, but are not limitedto, aliphatic hydrocarbons having from about 1 to about 20 carbon atomsper molecule. Preferably, that aliphatic hydrocarbon is a linearaliphatic hydrocarbon and has from 1 to 15 carbon atoms per molecule.Exemplary saturated hydrocarbons include, but are not limited to,methane, propane, butane, pentane, hexane, octane, and/or 1-decane.

Preferably, the oligomerization catalyst system is washed with asaturated hydrocarbon wash solution until a clear filtrate is observed.After washing, the solid catalyst system can be stored under a dry,inert atmosphere until ready for use. The washed, solid catalyst systemcan then be feed directly to an oligomerization reactor. In a secondembodiment, the catalyst system can be prepared in-situ, directly in anoligomerization reactor. A chromium source, pyrrole-containing compound,the dried treated support, and a metal alkyl can be charged directly tothe trimerization reactor. The presence of an unsaturated hydrocarbon isprovided by one or more of the oligomerization reactants in the reactor.The pressure and temperature of the reactor, both before and during anoligomerization reaction, are suitable to form an effective catalystsystem.

The reaction pressure, during catalyst system preparation, can be anypressure which does not adversely effect the reaction. Generally,pressures within the range of from about atmospheric pressure to aboutthree atmospheres are acceptable. For ease of operation atmosphericpressure is generally employed.

The reaction temperature, during catalyst system preparation, can be anytemperature. In order to effectuate a more efficient reaction,temperatures which maintain the reaction mixture in a liquid state, forreasons given above, are preferred.

The reaction time, during catalyst system preparation, can be any amountof time necessary for the reaction to occur. The reaction can beconsidered a dissolution process; any amount of time whereinsubstantially all soluble reactants can be dissolved is sufficient.Depending on the reactants, as well as the reaction temperature andpressure, reaction time can vary. Times of less than about 1 day can besufficient. Usually, reaction time is less than about 60 minutes. Underoptimum conditions, the reaction time can be within the range of fromabout I second to about 15 minutes. Longer times usually provide noadditional benefit and shorter times may not allow sufficient time forcomplete reaction.

Reactants

Oligomerization, as used in this disclosure, is defined as thecombination of any two, three, or more olefins. For example,oligomerization can be a reaction wherein the number of olefin, i.e.,carbon-carbon double bonds is reduced by two. Reactants applicable foruse in the trimerization process of this invention are olefiniccompounds which can a) self-react, i.e., oligomerize to give usefulproducts such as, for example, the self reaction of ethylene can giveone hexene and the self-reaction of 1,3-butadiene can give1,5-cyclooctadiene; and/or b) olefinic compounds which can react withother olefinic compounds, i.e., co-oligomerize, to give useful productssuch as, for example, co-oligomerize of ethylene plus hexene can giveone decene and/or 1-tetradecene, co-oligomerize of ethylene and 1-butenegives one octene, co-oligomerize of 1-decene and ethylene can give1-tetradecene and/or 1-docosene, or co-oligomerize of 1,3-butadiene and1,5-hexadiene can give 1,5, -cyclo-decadiene. For example, the number ofolefin bonds in the combination of three ethylene units is reduced bytwo, to one olefin bond, in 1-hexene. In another example, the number ofolefin bonds in the combination of two 1,3-butadiene units, reduced bytwo, to two olefin bonds in 1,5-cyclooctadiene. As used herein, the term"oligomerization" is intended to include dimerization of diolefins, aswell as "co-oligomerization", both as defined above.

Suitable oligomerizable olefin compounds are those compounds having fromabout 2 to about 30 carbon atoms per molecule and having at least oneolefinic double bond. Exemplary mono-1-olefin compounds include, but arenot limited to acyclic and cyclic olefins such as, for example,ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene,2-pentene, 1-hexene, 2-hexene, 3-hexene, 1-heptene, 2-heptene,3-heptene, the four normal octenes, the four normal nonenes, andmixtures of any two or more thereof. Exemplary diolefin compoundsinclude, but are not limited to, 1,3-butadiene, 1,4-pentadiene, and1,5-hexadiene. If branched and/or cyclic olefins are used as reactants,while not wishing to be bound by theory, it is believed that sterichindrance could hinder the oligomerization process. Therefore, thebranched and/or cyclic portion(s) of the olefin preferably should bedistant from the carbon-carbon double bond.

Catalyst systems produced in accordance with this invention preferablyare employed as oligomerization catalyst systems.

Reaction Conditions

The reaction products, i.e., olefin oligomers as defined in thisspecification, can be prepared from the catalyst systems of thisinvention by solution reactions, slurry reactions, and/or gas phasereaction techniques using conventional equipment and contactingprocesses. Contacting of the monomer or monomers with a catalyst systemcan be effected by any manner known in the art of solid catalysts. Oneconvenient method is to suspend the catalyst system in an organic mediumand to agitate the mixture to maintain the catalyst system in suspensionthroughout the trimerization process. Other known contacting methods,such as, for example, fluidized bed, gravitating bed, and fixed bed canalso be employed.

Reaction temperatures and pressures can be any temperature and pressurewhich can trimerize the olefin reactants. Generally, reactiontemperatures are with,in a range of about 0° to about 250° C.Preferably, reaction temperatures within a range of about 60° to about200° C. and most preferably, within a range of 80° to 150° C. areemployed. Generally, reaction pressures are within a range of aboutatmospheric to about 2500 psig. Preferably, reaction pressures within arange of about atmospheric to about 1000 psig and most preferably,within a range of 300 to 700 psig are employed.

Too low of a reaction temperature can produce too much undesirableinsoluble product and too high of a temperature can cause decompositionof the catalyst system and reaction products. Too low of a reactionpressure can result in low catalyst system activity. Too high of apressure can cause production of too much undesirable insoluble product.

Optionally, hydrogen can be added to the reactor to accelerate thereaction and/or increase catalyst system activity.

Catalyst systems of this invention are particularly suitable for use inoligomerization processes. The slurry process is generally carried outin an inert diluent (medium), such as a paraffin, cycloparaffin, oraromatic hydrocarbon. Exemplary reactor diluents include, but are notlimited to, isobutane and cyclohexane. Isobutane can decrease theswelling of the polymer product and enhance heterogeneous catalystactivity. However, a homogenous oligomerization catalyst system is moresoluble in cyclohexane. Therefore, a preferred diluent for a homogeneouscatalyzed oligomerization process is cyclohexane. When the reactant ispredominately ethylene, a temperature in the range of about 0° to about300° C. generally can be used. Preferably, when the reactant ispredominately ethylene, a temperature in the range of about 60° to about110° C. is employed.

Products

The olefinic products of this invention have established utility in awide variety of applications, such as, for example, as monomers for usein the preparation of homopolymers, copolymers, and/or terpolymers.

The further understanding of the present invention and its advantageswill be provided by reference to the following examples.

EXAMPLES Example I

In the following Runs, all catalyst systems were prepared in aglove-box, under dry nitrogen at ambient temperature and pressure. Thecatalyst support was weighed into a glass vial. Catalyst supports werealuminophosphate supports, prepared in accordance with U.S. Pat. No.4,364,855, activated at 700° C., with a P/Al molar ratio of 0.4 or 0.9.Runs 101-111, 118-120 and 125 had a support P/Al molar ratio of 0.4.Runs 112-117 and 121-124 had a support P/Al molar ratio of 0.9. Then,toluene and a solution of triethylaluminum (TEA) in toluene were addedto the support. The support, TEA, and toluene slurry was shaken forabout 24 hours in all Runs, except Runs 114-117 and 121-125, which wereshaken for about 4 days. Thus, all supports in Example I were treatedwith metal alkyl (TEA) and an unsaturated hydrocarbon (toluene), priorto contacting a chromium source.

Then chromium pyrrolide dimethoxyethane ([Na(DME)₂ ][Cr(C₄ H₄ N)₃Cl.DME]), (Cr(Py)₃ DME) was added to the support slurry and shaken againat ambient temperature and pressure. Runs 101-103, were shaken for 6days; Runs 104-113 and 118-120 were shaken for 24 hours; Runs 114-117and 121 were shaken for 4 days. A brown slurry was produced.

Excess liquid was decanted, the remaining solids were washed withcyclohexane until a clear wash solution was observed. The solids werevacuum dried at ambient temperature (about 20° C.) and stored under drynitrogen until use.

All oligomerization Runs were carried out in a two liter reactor underslurry (particle form) conditions. The diluent was isobutane and thereactor temperature was 90° C., except Runs 113, 115 and 118 where thereactor temperature was 70° C.; Runs 113 where the reactor temperaturewas 110° C.; and Run 117 where the reactor temperature was 100° C.Reactor pressure held at 550 psig during the oligomerization, withethylene being fed on demand.

The actual charging of the reactor was accomplished by the followingmethod. After purging the reactor at 100° C. with a stream of nitrogenfor at least 15 minutes, the reactor temperature was lowered to 90° C.,unless otherwise indicated, and a preweighed amount of supportedchromium pyrrolide catalyst system, unless otherwise indicated, wascharged against a slight countercurrent of nitrogen. One liter ofisobutane was then charged to the reactor and finally the reactorpressurized with ethylene.

The ethylene consumed was determined using a precalibrated ethylene flowmeter. Samples of the liquid product mixture were taken after a 30minute run time, without depressurizing the reactor by filling to200-300 psig a steel sampling cylinder adapted to the reactor with a diptube fitted with a fritted tip extending into the bottom of the reactorvessel. Samples were analyzed by gas chromatography and gaschromatography-mass spectrometry. Selectivities were normalized to 100%.Solid products were obtained by venting the reactor to atmosphere anddecanting the liquids from the solid material. The solids were thendried at 100° C. in a vacuum oven and weighed. The yield of solidproduct was obtained by weighing the combined solid and catalystresidues and subtracting from this the preweighed catalyst charge. Theyield of volatile products was obtained by subtracting the yield ofsolid products from the grams of ethylene consumed as recorded by theflow meter.

Activity typically ranged from 300-1500 g product/g catalyst/hourcalculated for 30 minute run time, as shown in Table I. The productobtained typically was represented by 97-99.5% by weight liquids and0.5-3% by weight polymer (wax). The liquid fraction was typically 85%hexenes, 11% decenes, 2% tetradecences, based on the total weight of theliquid fraction. The balance of the liquid product mixture was a tracelevel distribution of olefins typically totaling about 1-2% by weight ofthe product mixture.

                                      TABLE I                                     __________________________________________________________________________              Grams    Produc-                                                       Amount Cr  Grams                                                                              tivity, g                                                                           Total                                                                             Weight                                                                             Weight                                         TEA added                                                                            Cmpd.                                                                             Catalyst                                                                           prod./g                                                                             Grams                                                                             Percent                                                                            Percent                                     Run                                                                              to Reactor                                                                           Used                                                                              Charged                                                                            Cat./hr                                                                             Prod..sup.a                                                                       Solid.sup.a                                                                        Liquid                                                                             Observations                           __________________________________________________________________________    101                                                                              1.5 ml, 1.3%                                                                         0.110                                                                             0.3326                                                                             1190  207 2    98   --                                     102                                                                              2.5 ml, 1.3%                                                                         0.110                                                                             0.2106                                                                              900   95 3    97   --                                     103                                                                              1.8 ml, 1.3%                                                                         0.110                                                                             0.2964                                                                              915  137 3    97   --                                     104                                                                              1.5 ml, 1.3%                                                                         0.210                                                                             0.4706                                                                             1150  271 2    98   --                                     105                                                                              1.5 ml, 1.3%                                                                         0.210                                                                             0.0564                                                                             no activity                                                                         --  --   --   small amount tan                                                              powder                                 106                                                                              1.5 ml, 1.3%                                                                         0.210                                                                             0.3878                                                                             1300  271 1    99   --                                     107                                                                              1.5 ml, 1.3%                                                                         0.210                                                                             0.1345                                                                             no activity                                                                         --  --   --   small amount brown                                                            powder; smell of                                                              ether                                  108                                                                              1.5 ml, 1.3%                                                                         0.210                                                                             0.1577                                                                             .sup. 2560.sup.b                                                                    116 2    98   --                                     109                                                                              0      0.210                                                                             0.1895                                                                             1650  142 <1   >99  --                                     110                                                                              1.5 ml, 0.5%                                                                         0.326                                                                             0.3126                                                                              810  128 2    98   --                                     111                                                                              1.5 ml, 0.5%                                                                         0.210                                                                             0.5314                                                                              770  204 2    98   --                                     112                                                                              1.5 ml, 0.5%                                                                         0.210                                                                             0.1836                                                                              530   49 2    98   --                                     113                                                                              0      0.210                                                                             0.3208                                                                              440   71 1    99   --                                     114                                                                              1.5 ml, 0.5%                                                                         2.25                                                                              0.3555                                                                              910  161 1    99   waxy solids                            115                                                                              1.5 ml, 0.5%                                                                         2.25                                                                              0.1354                                                                             1550  106 1    99   --                                     116                                                                              1.5 ml, 0.5%                                                                         2.25                                                                              0.1574                                                                             1550  122 1    99   --                                     117                                                                              1.5 ml, 0.5%                                                                         2.25                                                                              0.1693                                                                             1170   98 1    99   --                                     118                                                                              1.5 ml, 0.5%                                                                         0.225                                                                             0.2034                                                                             1180  120 <1   >99  --                                     119                                                                              1.5 ml, 0.5%                                                                         0.225                                                                             0.2961                                                                             1070  158 <1   >99  --                                     120                                                                              1.5 ml, 0.5%                                                                         0.225                                                                             0.3357                                                                              620  104 2    98   --                                     121                                                                              1.0 ml, 1.0%                                                                         2.25                                                                              0.3801                                                                              840  159 3    97   --                                     122                                                                              1.0 ml, 1.0%                                                                         2.25                                                                              0.0392                                                                             1960  247 3    97   --                                     123                                                                              1.0 ml, 1.0%                                                                         2.20                                                                              0.3879                                                                             1000  194 4    96   700 psig in reactor;                                                          30 psig H.sub.2 added                                                         before ethylene                        124                                                                              0      2.20                                                                              0.2419                                                                             1040  129 2    98   added 30 psig H.sub.2                                                         after 15 minutes                       125                                                                              1.5 ml, 1.0%                                                                         2.23                                                                              0.5500                                                                              630  173 3    97   cyclohexane diluent,                                                          not iso-butane                         __________________________________________________________________________     .sup.a Including residual catalyst system.                                    .sup.b 15 minute run time                                                

The data in Table I show that catalyst systems prepared with a supportpre-treated with a metal alkyl and an unsaturated hydrocarbon produce asmall amount of polymer (wax) and a high quantity of liquid olefins.

Example II

In the following Runs, all catalyst systems were prepared in aglove-box, under dry nitrogen at ambient temperature and pressure. Thecatalyst support was weighed into a glass vial. Catalyst supports wereeither aluminophosphate supports, prepared in accordance with U.S. Pat.No. 4,364,855, activated at 700° C., with P/Al molar ratio of 0.4 or0.9; alumina (Al₂ O₃), commercially available from Akzo Chemic America,as Ketjen B, activated at 600° C. The support in Run 201 was alumina.Run 206-207, 211 and 212 had a support P/Al molar ratio of 0.4. Runs207-210 had a support P/Al molar ratio of 0.9. Then, a chromium sourceand optionally TEA and/or toluene were added to the support. Thus, noneof the supports in Example II were treated with a metal alkyl and/or anunsaturated hydrocarbon prior to contacting a chromium source. Thechromium sources given in Table II are chromium pyrrolidedimethoxyethane ([Na(DME)₂ ][Cr(C₄ H₄ N)₃ Cl.DME]), (Cr(Py)₃ DME);cyclopentadienyl chromium (Cr(C₅ H₅)₂), (CrCp₂); and bis-benzenechromium (Cr(C₆ H₆)₂), (Cr(Ben)₂). Runs 203-206, 211 and 212 did nothave triethylaluminum (TEA) added to the vial. Runs 207-210 did not haveadditional toluene added to the vial. The slurry was shaken for about 24hours in all Runs except Runs 203-204, which were shaken for about 30minutes.

Excess liquid was decanted, the remaining solids were washed withcyclohexane until a clear wash solution was observed. The solids weredried under vacuum at ambient temperature (about 20° C.) and storedunder dry nitrogen until used.

All oligomerization runs were carried out in a 2 liter reactor underslurry (particle form) conditions. The diluent was isobutane and thereactor temperature was 90° C., except Run 207 where the reactortemperature was 70° C., Run 208 where the reactor temperature was 80°C., Run 209 where the reactor temperature was 100° C., and Run 210 wherethe reactor temperature was 110° C. Reactor pressure was held at 550psig during the oligomerization, with ethylene being fed on demand.

The reactor was charged as described in Example I. Ethylene consumptionand product analyses were done as described in Example I,

The results of the oligomerization Runs are given in Table II.

                                      TABLE II                                    __________________________________________________________________________                           Grms      Produc-                                         Amount TEA Used     Cr   Grms tivity,g                                                                           Total                                      TEA Added.sup.a                                                                      in catalyst                                                                         Cr     Cmpd Catalyst                                                                           prod./g                                                                            Grms                                                                              Wt. %                                                                             Wt. %                           Run                                                                              to Reactor                                                                           Prep  Cmpd   Used Charged                                                                            cat./hr.                                                                           Prod.                                                                             Solid                                                                             Liquid                                                                            Observations                __________________________________________________________________________    201                                                                              1.5 ml, 1.3%                                                                         yes   CrPy.sub.3 DME                                                                       0.10 0.2216                                                                              460  51  2  98   --                         202                                                                              1.5 ml, 0.5%                                                                         yes   CrPy.sub.3 DME                                                                       0.2259                                                                             0.6213                                                                              440 136 <1  >99 waxy solids                 203                                                                              0.5 ml, 0.5%                                                                         no    CrCp.sub.2                                                                           0.10 0.1403                                                                              510  24 83  17   --                         204                                                                              0.5 ml, 0.5%                                                                         no    Cr(Ben).sub.2                                                                        0.10 0.2629                                                                              770 101 75  25  solid polymer                                                                 appears wet;                                                                  heavy odor of                                                                 olefins                     205                                                                              0      no    Cr(Ben).sub. 2                                                                       0.10 0.1834                                                                              630  58 79  21  polymer had                                                                   olefin odor                 206                                                                              1.5 ml, 0.5%                                                                         no    Cr(Ben).sub.2                                                                        0.10 0.5441                                                                             1050 287 >99 <1  solid polymer                                                                 appears wet;                                                                  olefin odor                 207                                                                              1.5 ml, 0.5%                                                                         yes   CrPy.sub.3 DME                                                                       0.10 0.3532                                                                             2550 180  2  98   --                         208                                                                              1.5 ml, 0.5%                                                                         yes   CrPy.sub.3 DME                                                                       0.10 0.1329                                                                             1930 118 17  83   --                         209                                                                              1.5 ml, 0.5%                                                                         yes   CrPy.sub.3 DME                                                                       0.10 0.0745                                                                             2950 110  1  99  low catalyst                                                                  charge                      210                                                                              1.5 ml, 0.5%                                                                         yes   CrPy.sub.3 DME                                                                       0.10 0.0912                                                                             2390 109  1  99   --                         211                                                                              0.5 ml, 1.0%                                                                         no    Cr(Ben).sub.2                                                                        0.978                                                                              0.3571                                                                             1240 222 86  14   --                         212                                                                              0.5 ml, 1.0%                                                                         no    CrCp.sub.2                                                                           0.914                                                                              0.6043                                                                              170  35 >99 <1  polymer damp;                                                                 smelled of                                                                    olefins                     __________________________________________________________________________

Comparison of the data in Table II with the data in Table I shows thatpre-treatment of a support with a metal alkyl and an unsaturatedhydrocarbon consistently results in low polymer and high liquidproduction. The data in Table II also show that the presence of apyrrole-containing compound can improve the percentage product yield ofliquids.

While this invention has been described in detail for the purpose ofillustration, it is not to be construed as limited thereby but isintended to cover all changes and modifications within the spirit andscope thereof.

That which is claimed is:
 1. A composition comprising:a) a modifiedinorganic oxide composition comprising an inorganic oxide selected fromthe group consisting of silica, silica-alumina, alumina, fluoridedalumina, silated alumina, thoria, aluminophosphate, aluminum phosphate,phosphated silica, phosphated alumina, silica-titania, coprecipitatedsilica/titania, fluorided/silated alumina, and mixtures thereof; a metalalkyl selected from the group consisting of alkyl aluminum compounds,alkyl boron compounds, alkyl magnesium compounds, alkyl zinc compounds,alkyl lithium compounds, and mixtures thereof; and an unsaturatedhydrocarbon; b) a metal source which is a chromium compound and; c) apyrrolide compound; d) wherein said metal source and said pyrrolidecompound are supported on the modified inorganic oxide support.
 2. Acomposition according to claim 1 wherein said pyrrolide compound isselected from the group consisting of pyrrole, derivatives of pyrrole,metal pyrrolides, and mixtures thereof.
 3. A composition according toclaim 2 wherein said pyrrolide compound is selected from the groupconsisting of pyrrole, 2,5-dimethylpyrrole, and mixtures thereof.
 4. Aprocess to prepare a modified inorganic oxide support compositioncomprising:a an inorganic oxide selected from the group consisting ofsilica, silica-alumina, alumina, fluorided alumina, silated alumina,theoria, aluminophosphate, aluminum phosphate, phosphated silica,phosphated alumina, silica-titania, coprecipitated silica/titania,flurorided/silated alumina, and mixtures thereof; b) a metal alkylselected from the group consisting of alkyl aluminum compounds, alkylboron compounds, alkyl magnesium compounds, alkyl zinc compounds, alkyllithium compounds, and mixtures thereof; and c) an unsaturatedhydrocarbon.
 5. A process according to claim 4 further comprisingrecovering a solid product.
 6. A process according to claim 4 furthercomprising contacting said modified inorganic oxide with:a) a metalsource which is a chromium compound and; b) a pyrrolide compound; c)wherein said metal source and said pyrrolide compound are supported onthe modified inorganic oxide support.
 7. A process according to claim 6wherein said unsaturated hydrocarbon is an aromatic hydrocarbon havingless than about 70 atoms per molecule.
 8. A process according to claim 4further comprising contacting said modified inorganic oxide with a metalsource which is a chromium compound and a pyrrolide compound.
 9. Aprocess according to claim 8 further comprising recovering a solidproduct.
 10. A process according to claim 5 further comprisingcontacting said recovered solid with a metal source which is a chromiumcompound, a pyrrolide compound, a metal alkyl selected from the groupconsisting of alkyl aluminum compounds, alkyl boron compounds, alkylmagnesium compounds, alkyl zinc compounds, alkyl lithium compounds, andan unsaturated hydrocarbon.
 11. A process according to claim 10 furthercomprising recovering a solid product.
 12. A process according to claim8 wherein said pyrrolide compound is selected from the group consistingof pyrrole, derivatives of pyrrole, metal pyrrolides, and mixturesthereof.
 13. A process according to claim 12 wherein said pyrrolidecompound is selected from the group consisting of pyrrole,2,5-dimethylpyrrole, and mixtures thereof.
 14. An inorganic oxidesupport prepared in accordance with claim
 4. 15. A catalyst systemprepared in accordance with claim
 6. 16. A catalyst system prepared inaccordance with claim 9.